Resin article

ABSTRACT

Provided is a resin article produced by melt processing and having layers formed by a layer-separation. having a layer-separated structure. The resin article may include a first resin layer and a second resin layer formed on the first resin layer. Also, the component of the first resin layer is detected on a surface of the second resin layer by infrared spectrometer. The resin article may have improved mechanical and surface characteristics. Further, since coating or plating is not required for manufacturing a resin article, a manufacturing time and/or cost can be reduced, and productivity can be increased.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of International ApplicationPCT/KR2011/003887, with an international filing date of May 26, 2011,which claims priority to and the benefit of Korean Patent ApplicationNo. 2010-0050639, filed May 28, 2010, Korean Patent Application No.2010-0050640, filed May 28, 2010, Korean Patent Application No.2010-0081084, filed Aug. 20, 2010, Korean Patent Application No.2010-0081085, filed Aug. 20, 2010, and Korean Patent Application No.2011-0050135, filed May 26, 2011, the disclosures of which areincorporated herein by reference in their entireties.

BACKGROUND

Plastic resins have various applications including automobile parts,helmets, parts of electric devices, parts of textile spinning machines,toys or pipes because of their easy processability and excellentproperties such as tensile strength, modulus of elasticity, heatresistance and impact resistance.

Particularly, home appliance functions as home interior accessories aswell as its own function as home appliance and parts of automobiles andtoys are in direct contact with a human body, these products arerequired to be environment-friendly and to have excellent scratchresistance. However, plastic resins are generally decomposed by oxygenin the air, ozone and light and easily changed in color when exposed toan external environment for over a certain period of time. As a result,plastic resins suffer from decrease of weather resistance and strength,which makes them to be easily broken. Thus, an additional coating orplating process has been usually applied to plastic resins to improvethese problems and surface properties. However, such a coating orplating process can drop efficiency and economic feasibility of amanufacturing process of plastic resins or generate large amount oftoxic materials during the process or disposal of a product.

Accordingly, various methods have been suggested to improve propertiesof plastic resins such as scratch resistance, heat resistance andweather resistance without using an additional coating or platingprocess. For example, a method of adding inorganic particles to highmolecule resins has been suggested to improve physical properties suchas abrasion resistance and stiffness of the resins. However, this methodmay deteriorate the processability of plastic resins and impact strengthand gloss due to the addition of inorganic particles. In addition, ithas been suggested using a method of adding resins that have excellentscratch resistance or thermal resistance to improve surface propertiesof plastic resins. However, this method requires additional processingsuch as for curing resin products produced by injection and fails toimprove weather resistance, thermal resistance or scratch resistance tothe level required for resin articles.

SUMMARY OF THE INVENTION

The present invention provides a resin article produced by meltprocessing (“melt-produced resin article”) and having layers formed by alayer separation. The resin article may have improved mechanical andsurface characteristics. Further, since a separate step for coating orplating is not required for manufacturing the resin article, amanufacturing time and/or manufacturing cost can be reduced, andproductivity can be increased.

In one embodiment, a resin article produced by melt processing thatincludes a first resin layer; and a second resin layer formed on thefirst resin layer. These layers are formed by a layer-separation duringthe melt processing. Here, the component of the first resin layer isdetected on a surface of the second resin layer by an infrared (IR)spectrometer.

In another embodiment, a resin article produced by melt processingincludes a first resin layer; a second resin layer formed on the firstresin layer; and an interface layer formed between the first resin layerand the second resin layer. These layers are formed by alayer-separation during the melt processing. Here, the interface layerincludes the first resin and the second resin.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will become more apparent to those of ordinary skill in theart by describing in detail exemplary embodiments thereof with referenceto the attached drawings, in which:

FIG. 1 is an illustrative schematic diagram showing a resin blend,according to one embodiment of the present invention.

FIG. 2 is an illustrative schematic diagram showing a resin blend,according to another embodiment of the present invention.

FIG. 3 is a SEM image illustrating a cross-sectional view of amelt-processed resin article prepared according to Example 1.

FIG. 4 is an illustrative schematic diagram showing a melt-processedresin article including a first resin layer, a second resin layer and aninterface layer formed between the first and the second resin layer,according to one embodiment of the present invention.

FIG. 5 is an illustrative schematic diagram showing a melt-processedresin article including a first resin layer and a second resin layer,according to one embodiment of the present invention.

FIG. 6 is an illustrative schematic diagram showing a melt-processedresin article including a first resin layer, a second resin layer and athird resin layer, according to another embodiment of the presentinvention.

FIG. 7 is an illustrative schematic diagram showing a melt-processedresin article, according to another embodiment of the present invention.

FIG. 8 is an illustrative schematic diagram showing a pellet having acore and a shell.

FIG. 9 is a SEM image illustrating a cross-sectional view of amelt-processed resin article treated with a solution capable ofselectively dissolving a second resin, when viewed at a 45-degree anglefrom the surface prepared according to Example 1.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, a melt-processed resin article and a method of preparingthe resin article according to embodiments of the present invention willbe described in detail.

In one embodiment, a melt-processed resin article that includes a firstresin layer; and a second resin layer formed on the first resin layer.These layers are formed by a layer-separation during the meltprocessing. Here, the component of the first resin layer is detected ona surface of the second resin layer by an infrared (IR) spectrometer.

A structure of the resin article, that is, a structure in which thecomponent of the first resin layer is detected from the surface of thesecond resin layer by the IR spectrometer, is novel, and has not beenknown in the art. Generally, in the case of a second layer applied by acoating process, the component of the first resin layer is difficult tobe detected from the surface of the second resin layer.

The surface of the second resin layer refers to a surface exposed to theambient air, not to the first resin layer.

In addition, the component of the first resin layer refers to at leastone of the components included in the first resin layer.

When a resin blend including specific first and second resins is used,due to different physical properties between the first and secondresins, layer separation may occur. Specifically, in the case that theresin blend of the first and second resins is melt-processed, themelt-processed resin blend is exposed to an ambient air and the firstand second resins can be separated. Therefore, a resin article can havea structure in which a first resin layer may be divided from a secondresin layer via an interface layer and the second resin layer is exposedto an ambient air without using an additional process during a meltprocessing.

Such a structural characteristic of the resin article seems to beattributed to a resin blend comprising specific first and second resins.The specific first and second resins may be a resin which has certainphysical properties and/or a certain molecular weight distributionand/or a certain weight average molecular weight. Since the resinarticle has such a structural characteristic, the resin article may haveimproved mechanical and surface characteristics. Further, since coatingor plating is not required for manufacturing the resin article, amanufacturing time and/or cost can be reduced, and productivity can beincreased.

A “blend” may be a mixture of two or more different species of resins. Atype of blend may include, but is not limited, a mixture of two or moreresins in one matrix, or a mixture of two or more kinds of pellets.Particularly, the mixture of two or more resins in one matrix may be apellet containing a mixture of two or more resins. For example, amixture of a first resin and a second resin can be contained in a singlepellet. Alternatively, in the mixture of two or more kinds of pellets,each kind of pellet contains one kind of resin. For example, a blend caninclude a mixture of a pellet containing a first resin and a pelletcontaining a second resin.

A “melting process” or “melt processing” may refer to a process ofmelting the resin blend at not less than a melting temperature(Tm) ofthe resin blend to form a melt blend and forming a desired product byusing the melt blend. For example, the melting process or melt processmay include injection molding, extrusion, blow molding, expandingmolding and the like.

A “resin article” may indicate a product which is not treated by aseparate step for coating or plating after a resin blend ismelt-processed.

A “layer separation” may indicate that a portion of a resin blend thatis separated from the remaining resin blend by phase-separation, forms alayer that is visibly separated from a layer of the remaining resinblend. For example, the separated portion of the resin blend can be richwith or contain a substantial amount of a second resin and the remainingresin blend can be rich with or contain a substantial amount of a firstresin. The layer separation results in a layer-separated structure in aresin article or a pellet, which is distinguished from a sea-islandstructure where the phase-separated portion is partially distributed inthe entire resin blend. The layer separation of the resin blend resultsin two or more separate layers, preferably two separate layers formed ina resin article or a pellet prepared by the resin blend.

A “first resin” may indicate that a resin which may be included in thefirst resin layer. The first resin mainly determines physical propertiesof a desired article, and thus may be selected according to a kind ofthe desired article and process conditions used herein.

A “second resin” may indicate that a resin which may be included in thesecond resin layer. The second resin shows the difference in physicalproperties from the first resin as described above and may providespecific functions to a surface of the desired article, and thus thefunctions are not particularly limited.

Meanwhile, the resin article may include an interface layer including afirst resin and a second resin and formed between the first resin layerand the second resin layer. As shown in FIG. 3B, the interface layer mayserve as a boundary formed between the layer-separated first and secondresin layers, and include the first and second resins. In the interfacelayer, the first resin is physically or chemically bound to the secondresin, and the first resin layer may be bound to the second resin layerby the interface layer.

To observe the first and second resin layers and the interface layer andmeasure a thickness of each layer, a sample was cut with a diamond knifeusing a microtoming device to obtain a smooth cross-section, and thesmooth cross-section was etched using a solution capable of moreselectively dissolving a second resin than a first resin. The etchedcross-section is dissolved to different levels of depth according tocontents of the first and second resins, and when the cross-section isviewed at a 45-degree angle from a surface thereof through SEM, thefirst resin layer, the second resin layer and the interface layer may beobserved due to a shade difference and thicknesses thereof may bemeasured. In the present invention, as the solution more selectivelydissolving the second resin, a 1,2-dichloroethane solution (10 volume %,in EtOH) is used, but is merely an example. Therefore, any solutionhaving a higher solubility of the second resin than the first resin maybe used without limitation, and the solution may vary according to thekind and composition of the second resin. The thickness of the interfacelayer may be 0.01 to 95% or 0.1 to 70%, of the total thickness of thesecond resin layer and the interface layer. When the thickness of theinterface layer is 0.01 to 95% to the total thickness of the secondresin layer and the interface layer, the interface adhesive strength ofthe first and second resin layers is excellent. Thus, the first and thesecond resin layers are not detached, and the surface characteristicattributed to the second resin layer may be considerably improved. Onthe other hand, when the thickness of the interface layer is too smallerthan the total thickness of the second resin layer and the interfacelayer, the adhesive strength between the first and second resin layersis decreased, and thus both layers may be detached. However, when thethickness of the interface layer is too thick compared to the totalthickness of the second resin layer and the interface layer, theimprovement in a surface characteristic of the second resin layer may beinsignificant.

The second resin layer may have a thickness of 0.01 to 60%, 0.1 to 40%or 1 to 20%, of the total thickness of the resin article. As the secondresin layer has a thickness in a specific range, it can provide thesurface of the resin article with specific functions. Here, when thesecond resin layer is too thin, it may be difficult to sufficientlyimprove the surface characteristic of the resin article, and when thesecond resin layer is too thick, the mechanical property of the secondresin may be reflected to the resin article, and thus the mechanicalproperty of the first resin may be changed.

In another embodiment, a melt-processed resin article includes a firstresin layer; a second resin layer formed on the first resin layer; andan interface layer formed between the first resin layer and the secondresin layer. These layers are formed by a layer-separation during themelt processing. Here, the interface layer includes the first resin andthe second resin.

The resin article is formed in such a structure that the first resinlayer is separated from the second resin layer by an interface layer andthe second resin layer is exposed to an ambient air, which is a novelstructure that has not been known in the art. This structure may not beformed by extrusion and injection process of a general resin, and thusit is difficult to obtain the effects resulting from this novelstructure.

A structure of the resin article, as described above, may include aninterface layer comprising the first resin and the second resin andformed between the first resin layer and the second resin layer. Here, athickness of the interface layer may be 0.01 to 95% or 0.1 to 75%, of atotal thickness of the second resin layer and the interface layer.

In addition, the second resin layer may have a thickness of 0.01 to 60%,0.1 to 40% or 1 to 20%, of the total resin article.

As described above, the resin article may have such a structure in whichthe first resin layer is separated from the second resin layer by theinterface layer, and the second resin layer is exposed to the ambientair. For example, the resin article may have a structure in which afirst resin layer, an interface layer and a second resin layer aresequentially stacked as shown in FIG. 3, or a structure in which thefirst resin layer is disposed, and the interface layers and the secondresin layer are disposed above and below the first resin layer as shownin FIG. 4. Alternatively, the resin article may have such a structurethat the first resin layer formed in various three-dimensional shapes,for example, spherical, circular, polyhedral and sheet-type shapes, issequentially surrounded by the interface and the second resin layer.

A resin article formed by a melt processing using the resin blend mayhave improved mechanical and surface characteristics and may be easilyproduced with a reduced manufacturing cost and time. For example, theresin blend may be layer-separated by a melt processing to form a resinarticle having a specific function on a surface of the resin article,without an additional process, such as coating and plating.

The layer separation of the resin blend may be attributed to adifference in physical properties between first and second resins and/ora molecular weight distribution of the second resin and/or a weightaverage molecular weight of the second resin. Here, the differentphysical properties may, for example, include surface energy, meltviscosity and a solubility parameter. Although it is illustrated herethat two resins are blended for the purpose of explanation of thepresent invention, it will be apparent to one of skilled in the art thatthree or more resins having different physical properties may be blendedand separated during a melt processing.

In one embodiment, a resin article includes a first resin layer and asecond resin layer having a difference in surface energy from the firstresin layer at 25° C. of 0.1 to 35 mN/m, 1 to 30 mN/m, 1 to 20 mN/m.Such difference in surface energy can be 1 to 10 mN/m, 0.5 to 10 mN/m, 5to 35 mN/m, 15 to 35 mN/m or 5 to 30 mN/m. It will be apparent to one ofskilled in the art that the listed ranges are only examples for thepurpose of the description of the present invention and any valueswithin 0.1 to 35 mN/m can be chosen.

The difference in surface energy may refer to the difference in surfaceenergy between the first resin layer and the second resin layer or tothe difference in surface energy between the first resin and the secondresin.

When the difference in surface energy is too small, such as less than0.1 mN/m, the layer separation does not easily occur because the secondresin in a mixture of melting state is difficult to move through thepolymer matrix of the resin blend. When the difference in surface energyis too big such as greater than 35 mN/m, the first and second resins maynot be attached to each other, and thus may be detached.

The lower and/or upper limits of the difference in surface energy may beany numeric value of 0.1 to 35 mN/m, and be dependent on the propertiesof the first resin. Particularly, when a first resin is used as a baseresin and a second resin is used a functional resin to improve surfaceproperties of a first resin, the second resin may be selected such thata difference in surface energy between the first and second resins is0.1 to 35 mN/m at 25° C. Since a value of the surface energy of thesecond resin (e.g., functional resin) may be different based on theproperties of the first resin (e.g., base resin), the difference insurface energy may be determined based on the properties of the firstresin. The properties of the first resin may include, but is not limitedto, a kind of the first resin, or a value of the surface energy of thefirst resin. In one embodiment, the difference in surface energy may beselected by considering mobility of the second resin in a meltingmixture of the first and second resins.

By way of an example, in the case that the resin blend of the first andsecond resins having the difference in surface energy of 0.1 to 35 mN/mat 25° C. is used during manufacturing a melt-processed resin article,when the resin blend of the first and second resins is melt-processedsuch as extrusion or injection, the melt-processed resin blend isexposed to an ambient air. In the melt-processed resin blend, the firstand second resins can be separated due to the higher affinity of thesecond resin to the ambient air compared to the first resin.Particularly, the second resin having a smaller surface energy comparedto the first resin may have a hydrophobic property, and due to itsfluidity in the melt-processed resin blend, move to surface thatcontacts the ambient air. Thus, the second resin may be positionedadjacent to an ambient air to form a second resin layer as a surfacelayer. A first resin layer may be positioned on an inner side of thesecond layer. Accordingly, a layer separation can occur between thefirst and second resins of the resin blend.

The resin blend may be separated into two or more layers. The resinblend including the first resin and the second resin may belayer-separated into three layers, i.e., Second resin layer/First resinlayer/Second resin layer, as shown in FIG. 5, when two opposite sides ofthe melt-processed resin blend are exposed to the ambient air.Alternatively, when only one side of the melt-processed resin blend isexposed to the ambient air, the resin blend may be layer-separated intotwo layers, i.e., Second resin layer/First resin layer. Further, when aresin blend including a first resin, a second resin and a third resin ismelt-processed, the melt-processed resin blend may be layer-separatedinto five layer, i.e., Third resin layer/Second resin layer/First resinlayer/Second resin layer/Third resin layer, as shown in FIG. 6, by usingthe differences in surface energy among the three resins. Furthermore,when all sides of the melt-processed resin blend are exposed to theambient air, the resin blend may be layer-separated into all directionto form a core-shell structure, as shown FIG. 7.

In another embodiment, a resin article includes a first resin layer anda second resin layer having a difference in melt viscosity from thefirst resin layer of 0.1 to 3000 pa*s, 1 to 2000 pa*s, or 1 to 1000 pa*sat a shear rate of 100 to 1000 s⁻¹ and at a processing temperature of aresin blend including the first and second resins. Such a difference canalso be 100 to 500 pa*s, 500 to 3000 pa*s, 1500 to 3000 pa*s or 500 to2500 pa*s at a shear rate of 100 to 1000 s⁻¹ and at a processingtemperature of a resin blend including the first and second resins.

The difference in melt viscosity may refer to the difference in meltviscosity between the first resin layer and the second resin layer orthe difference in melt viscosity between the first resin and the secondresin.

It will be apparent to one of skilled in the art that the listed rangesare only examples for the purpose of description of the presentinvention and any value within the range of 0.1 to 3000 pa*s at theabove shear rate and at a processing temperature of a resin blend can beselected. When the difference in the melt viscosity is too low forexample less than 0.1 pa*s at the shear rate and at a processingtemperature of the resin blend, the layer separation of themelt-processed resin blend does not easily occur because the first andsecond resins are too easily mixed together. When the difference in themelt viscosity is too high for example greater than 3000 pa*s at theshear rate and at a processing temperature of the resin blend, the firstand second resins may not be attached to each other due to a highdifference of the melt viscosity and thus may be detached.

The lower and/or upper limits of the difference in melt viscosity may beany numeric value of 0.1 to 3000 pa*s, and be dependent on theproperties of the first resin. Particularly, when a first resin is usedas a base resin and a second resin is used as functional resin toimprove surface properties of the first resin, the second resin may bechosen such that a difference in a melt viscosity between the first andsecond resins is 0.1 to 3000 pa*s at a shear rate of 100 to 1000 s⁻¹.Since a value of the melt viscosity of the second resin (e.g.,functional resin) may be different based on the properties of the firstresin (e.g., base resin), the difference in the melt viscosity may bedetermined based on the properties of the first resin. The properties ofthe first resin may include, but is not limited to, a kind of the firstresin, or a value of the melt viscosity of the first resin. In oneembodiment, the difference in melt viscosity may be selected byconsidering fluidity of the second resin in a melting mixture of thefirst and second resins.

The resin blend of the first and second resins having the difference inmelt viscosity of 0.1 to 3000 pa*s at a shear rate of 100 to 1000 s⁻¹and at a processing temperature of the resin blend can be used. By wayof an example, in the case that the resin blend of the first and secondresins having the difference in melt viscosity of 0.1 to 3000 pa*s at ashear rate of 100 to 1000 s⁻¹ and at a processing temperature of theresin blend is used, when the resin blend of the first and second resinsis melt-processed such as extrusion or injection, the melt-processedresin blend is exposed to an ambient air. In the melt-processed resinblend, the first and second resins can be separated due to thedifference of fluidity between the first resin and second resin.Particularly, the second resin having a smaller melt viscosity comparedto the first resin may have a higher fluidity than the first resin, andmove to a surface that contacts the ambient air. Thus, the second resinmay be positioned adjacent to an ambient air to form a second resinlayer as a surface layer. A first resin layer may be positioned on aninner side of the second layer. Accordingly, a layer separation canoccur between the first and second resins of the resin blend.

The melt viscosity may be measured using a capillary flow meter, andindicates a shear viscosity (pa*s) at a predetermined processingtemperature and shear rate (/s). The shear rate is a shear rate appliedwhen the resin blend is processed, and may be selected depending on aprocessing method, for example, shear rate of 100 to 1000 s⁻¹. It willbe apparent to one of skilled in the art to control the shear rateaccording to the processing method.

The processing temperature is a temperature at which the resin blend isprocessed. For example, when the resin blend is subject to a meltprocessing such as extrusion or injection, the processing temperature isa temperature at which the melt processing such as extrusion orinjection is performed. The processing temperature may be controlledaccording to a resin subjected to melt processing such as extrusion orinjection. It will be apparent to one of skilled in the art to controlthe processing temperature according to the kinds of resins of the resinblend. For example, a temperature for extruding or injecting a resinblend including a first a an ABS resin as a first resin and a secondresin obtained by polymerizing a methyl methacrylate-based monomer maybe 210 to 240° C.

In still another embodiment, a resin article includes a first resinlayer and a second resin layer having a difference in solubilityparameter from the first resin layer at 25° C. of 0.001 to 10(J/cm³)^(1/2), 0.01 to 5 (J/cm³)^(1/2), or 0.01 to 3 (J/cm³)^(1/2). Suchdifference in solubility parameter can also be 0.01 to 2 (J/cm³)^(1/2),0.1 to 1 (J/cm³)^(1/2), 0.1 to 10 (J/cm³)^(1/2), 3 to 10 (J/cm³)^(1/2),5 to 10 (J/cm³)^(1/2), or 3 to 8 (J/cm³)^(1/2).

The difference in solubility parameter may refer to the difference insolubility parameter between the first resin layer and the second resinlayer or the difference in solubility parameter between the first resinand the second resin.

The lower and/or upper limit of the difference in solubility parametermay be any numeric value of 0.001 to 10 (J/cm³)^(1/2), and be dependenton a solubility parameter of the first resin. It will be apparent to oneof skilled in the art that the listed values are only examples for thepurpose of description of the present invention and any value within therange of 0.001 to 10 (J/cm³)^(1/2) at 25° C. can be chosen. A solubilityparameter is an intrinsic property of resin reflecting solubilitydepending on a polarity of each resin molecule, and the solubilityparameter for each resin is generally known. When the difference in thesolubility parameter is too small, for example, less than 0.001(J/cm³)^(1/2), the layer separation does not easily occur because thefirst and second resins are too easily mixed together. When thedifference in the solubility parameter is too big, for example, greaterthan 10 (J/cm³)^(1/2), the first and second resins may not be attachedto each other due to a high difference of solubility parameter, and thusmay be detached.

The lower and/or upper limits of the difference in solubility parametermay be any numeric value of 0.001 to 10 (J/cm³)^(1/2), and be dependenton the properties of the first resin. Particularly, when a first andsecond resins are used as a base and functional resins, respectively,the second resin may be chosen such that a difference in a solubilityparameter between the first and second resins is 0.001 to 10(J/cm³)^(1/2) at 25° C. Since a value of the solubility parameter of thesecond resin (e.g., functional resin) may be different based onproperties of the first resin (e.g., base resin), the difference in thesolubility parameter may be determined based on the properties of thefirst resin. The properties of the first resin may include, but is notlimited to, a kind of the first resin, or a value of the solubilityparameter of the first resin. In one embodiment, the difference insolubility parameter may be selected by considering immiscibilitybetween the first resin and the second resin in a melting mixture of thefirst and second resins.

By way of an example, in the case that the resin blend of the first andsecond resins having the difference in solubility parameter of 0.001 to10 (J/cm³)^(1/2) at 25° C. is used, when the resin blend of the firstand second resins is melt-processed, the melt-processed resin blend isexposed to an ambient air, the first and second resins can be separateddue to the degree of immiscibility between the first resin and secondresin. Particularly, the second resin having a difference in solubilityparameter from the first resin at 25° C. of 0.001 to 10 (J/cm³)^(1/2)may be immiscible with the first resin. Thus, the second resin havingadditionally lower surface tension or lower melt viscosity than that ofthe first resin may move and be positioned adjacent to an ambient air toform a second resin layer. A first resin layer may be positioned on aninner side of the second layer. Accordingly, a layer separation can beoccurred between the first and second resins of the resin blend.

In still another embodiment, a molecular weight distribution (PDI) ofthe second resin is 1 to 2.5, or 1 to 2.3, 1 to 2. The molecular weightdistribution can also be 1.3 to 2.5, 1.5 to 2.5, or 1.3 to 2.3. Thelower and/or upper limits of the molecular weight distribution (PDI) ofthe second resin may be any numeric value of 1 to 2.5. It will beapparent to one of skilled in the art that the listed ranges are onlyexamples for the purpose of the description of the present invention andany value within the range of 1 to 2.5 can be selected. When themolecular weight distribution of the second resin is greater than 2.5,the first resin is easily mixed with the second resin due to the lowmolecular weight portion of the second resin, or the mobility of thesecond resin in a mixture of melting state is degraded due to the highmolecular weight portion thereof, and thus the layer separation betweenthe first and second resin does not easily occur.

In still another embodiment, a weight average molecular weight (Mw) ofthe second resin is 30,000 to 200,000, or 50,000 to 150,000. The weightaverage molecular weight (Mw) of the second resin of the resin blend canalso be 50,000 to 200,000, 80,000 to 200,000, 80,000 to 150,000, 50,000to 120,000, or 80,000 to 120,000. The lower and/or upper limits of theweight average molecular weight (Mw) of the second resin may be anynumeric value of 30,000 to 200,000. It will be apparent to one ofskilled in the art that the listed ranges are only examples for thepurpose of the description of the invention and any value within therange of 30,000 to 200,000 can be chosen. When the weight averagemolecular weight is smaller than 30,000, the first resin is easily mixedwith the second resin, and when the weight average molecular weight isgreater than 200,000, the mobility of the second resin in a mixture ofmelting state is degraded and thus the layer separation between thefirst and second resin does not easily occur.

Meanwhile, the first resin may determine the physical properties of aresin article and may be selected according to any kind of the desiredresin article and processing conditions. As the first resin, a syntheticresin may be used without limitation, but may preferably include astyrene-based resin such as an acrylonitrile butadiene styrene(ABS)-based resin, a polystyrene-based resin, an acrylonitrile styreneacrylate (ASA)-based resin or a styrene-butadiene-styrene blockcopolymer-based resin; a polyolefin-based resin such as a high densitypolyethylene-based resin, a low density polyethylene-based resin or apolypropylene-based resin; a thermoplastic elastomer such as anester-based thermoplastic elastomer or olefin-based thermoplasticelastomer; a polyoxyalkylene-based resin such as apolyoxymethylene-based resin or a polyoxyethylene-based resin; apolyester-based resin such as a polyethylene terephthalate-based resinor a polybutylene terephthalate-based resin; a polyvinylchloride-basedresin; a polycarbonate-based resin; a polyphenylenesulfide-based resin;a vinyl alcohol-based resin; a polyamide-based resin; an acrylate-basedresin; engineering plastics; or a copolymer or mixture thereof.

The engineering plastics are a group of plastics that exhibit superiormechanical and thermal properties. By way of examples, polyetherketone,polysulphone, polyimides and the like may be used as the engineeringplastics.

The second resin shows the difference in physical properties from thefirst resin as described above, and may be chosen to provide specificfunctions to a surface of a resin article. The functions of the secondresins are not particularly limited. For example, the second resins maybe resins providing a high surface hardness function, an anti-wearfunction, an anti-contamination function, an anti-fingerprint function,a color, a pearling function, a high-gloss function, a non-glossfunction, a barrier function or a combination thereof.

The second resin may have either or all of a thermal curable functionalgroup and a radiation, such as UV, curable functional group withoutspecific limitation. When a thermal curable functional group is includedin the second resin, the layer separation occurs and hardness may beincreased due to the crosslinks formed in melt processing such asextrusion or injection.

As another examples of the second resin, a (meth)acrylate-based resin,an epoxy-based resin, an oxetane-based resin, an isocyanate-based resin,a silicon-based resin, a fluorine-based resin, or a copolymer or mixturethereof may be included.

The (meth)acrylate-based resin is a resin formed by polymerizing anacryl or methacryl monomer as a main component, which may include, butis not limited to, alkyl methacrylates such as methyl methacrylate,ethyl methacrylate, propyl methacrylate, butyl methacrylate, cyclohexylmethacrylate, octyl methacrylate, lauryl methacrylate or stearylmethacrylate; alkyl acrylates such as methyl acrylate, ethyl acrylate,propyl acrylate, butyl acrylate, octyl acrylate, lauryl acrylate orstearyl acrylate; or glycidyl(meth)acrylates such as glycidylmethacrylate or glycidyl acrylate.

The epoxy-based resin is a resin containing an epoxy group, and may be,but is not limited to, a bisphenol type such as bisphenol A, bisphenolF, bisphenol S or a hydro additive thereof; a novolac type such asphenol novolac or cresol novolac; a nitrogen-containing ring type suchas triglycidyl isocyanurate or hydantoin; an alicyclic type; analiphatic type; an aromatic type such as naphthalene or biphenyl; aglycidyl type such as glycidyl ether, glycidyl amine or glycidyl ester;a dicyclo type such as dicyclopentadiene; an ester type; or an etherester type.

The oxetane-based resin is a resin formed by polymerizing an oxetanemonomer having at least one oxetane ring, and may be, but is not limitedto, 1,4-bis[(3-ethyl-3-oxetanylmethoxy)methyl]benzene,di[1-ethyl(3-oxetanyl)]methylether, or a polyoxetane compound such asphenol novolac oxetane, terephthalate bisoxetane or biphenylenebisoxetane.

The isocyanate-based resin is a resin containing an isocyanate group,and may be, but is not limited to, diphenylmethane diisocyanate (MDI),toluene diisocyanate (TDI) or isophorone diisocyanate (IPDI).

The silicon-based resin is a resin containing a main chain connected bya siloxane bond which is a silicon-oxygen bond, and may be, but is notlimited to, polydimethylsiloxane (PDMS).

The fluorine-based resin is a resin containing a fluorine atom, and maybe, but is not limited to, polytetrafluoroethylene (PTFE),polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), orpolyvinylfluoride(PVF).

In another embodiment, a resin blend for forming a layer-separatedstructure includes a base resin and a functional resin. A value of asurface energy of the functional resin is different from that of thebase resin, and the value of the surface energy of the functional resinis dependent on properties of the base resin.

The base resin, for example, a first resin, may substantially determinethe physical properties of a resin article. The functional resin, forexample, a second resin, may provide specific functions to a surface ofa resin article. The properties of the base resin and the specificfunctions of the second resin are the same as described the above.

The present invention further provides a method of preparing amelt-processed resin article. The resin article has a layer-separatedstructure. In one embodiment, the method includes melting a blend offirst and second resins to form a melt blend and processing the meltblend to prepare the resin article and the surface energy differencebetween the first resin and the second resin is 0.1 to 35 mN/m at 25° C.

As described above, since the second resin has different properties fromthe first resin such as higher hydrophobicity due to the difference inphysical properties such as a surface energy, the layer separation mayoccur during the melt processing such as injection or extrusion of theresin blend. This layer separation enables a layer of the second resinto be formed on a surface of a melt-processed resin article. Themelt-processed resin article thus produced has excellent properties andsurface characteristics and thus does not need of additional process forcoating or painting. As a result, a manufacturing time and/or cost canbe reduced, and productivity can be increased. Further, since the secondresin can be formed to have a function such as gloss oranti-contamination and can be separated from the first resin during themelt processing of the resin blend, the resin article in which the firstresin constitutes a body and the second resin forms a surface on thebody can be easily manufactured without performing additional process.Still further, when the first and second resins are used to form apellet, the pellet having a core of the first resin and a shell of thesecond resin can be manufactured by the melt processing of the resinblend without performing any additional process. Furthermore, the meltprocessing may be performed under a shear stress, and may include, butis not limited to, injection and extrusion.

When the resin blend described above is used, layer separation occursdue to the difference in physical properties between the first resin andthe second resin. For this reason, it is completely different from theconventional method using a solvent having a low viscosity to easilypull an article out of a mold. In the present invention, since at leasttwo layer-separable resins are used, surface and mechanicalcharacteristics of the final resin article may be improved. However, theconventional method using the solvent having a low viscosity is foreasily removing the article from a mold, but has no effect on a physicalproperties of the final product.

In the formation of the resin blend of the first resin and the secondresin, a method or device conventionally known to be used to blend aplastic resin, a polymer or a copolymer may be used without limitation.In one embodiment, the resin blend may be prepared to include a firstresin and a second resin that have a difference in physical properties,for example, surface energy, melt viscosity or solubility parameter. Theresin blend may be melted to form a melt blend and the melt blend may befurther processed to form resin article that has a layer-separatedstructure. For example, the melted resin blend may be subject to anextrusion process to prepare a pellet. As described above, the first andsecond resins may be separated during the melt processing such asextrusion. Particularly, the second resin may move to contact with anambient air due to its hydrophobic property compared to the first resin.A second resin layer may be positioned adjacent to an ambient air, and alayer substantially formed of a first resin layer may be positioned onan opposite side to the ambient air but disposed adjacent to the secondresin layer. Accordingly, the resin article may have a body that isformed of the first resin and a surface that is on the body and isformed of the second resin.

The resin blend including the first and second resins may be preparedinto a pellet using a melt processing. The pellet may have a core havinga first resin and a shell having a second resin. That is, the firstresin is disposed in the middle thereof, and a second resin islayer-separated from the first resin and disposed to surround the firstresin and to form a shell of the pellet. It can be illustrated as inFIG. 8.

The first resin and the second resin have different properties asdescribed above. That is, the first resin and the second resin may havea difference in surface energy from the first resin at 25° C. of 0.1 to35 mN/m; a difference in melt viscosity of 0.1 to 3000 pa*s at a shearrate of 100 to 1000 s⁻¹ and at a processing temperature of the pellet;or a difference in solubility parameter of 0.001 to 10.0 (J/cm³)^(1/2)at 25° C. Further, the second resin may have a molecular weightdistribution (PDI) of 1 to 2.5 or a weight average molecular weight (Mw)of 30,000 to 200,000. The first and second resins have already beendescribed in detail, and thus further detailed description will beomitted.

In another embodiment, the pellet may be further processed to form aresin article. For example, the pellet having first and second resins ofdifferent physical properties may be melted and further processed, forexample, injected, to form a final product, for example, a resinarticle. As described above, due to the difference in various physicalproperties, for example, surface energy, melt viscosity or solubilityparameter, of the first and second resins of the pellets, the resinarticle formed using the pellets may have separated layers, i.e., a bodyformed of the first resin and a surface layer formed of the second resinand placed on the body. Although it is illustrated that the pellets ofcore-shell structure having the first and second resins aremelt-processed to form a resin article for the purpose of explanation,it will be apparent to one of skilled in the art that a mixture of twoor more pellets or pellets including the composition of two or moreresins may be used to form a resin article. Alternatively, the resinblend may be directly prepared into a resin article through the meltprocessing, as described above. The processing temperature to be appliedmay be changed depending on kinds of the first and second resins used inthe melt processing of the resin blend.

In some embodiments, the method of preparing a melt-processed resinarticle may further include curing a product having a layer-separatedstructure (for example, a resin article having a body and a surfacelayer on the body) obtained by melt processing the resin blend. Forexample, after an extrusion or injection, thermal curing and/orradiation curing, such as UV curing, may be further performed on themelt-processed product. When necessary, chemical or physical treatment,such as a heat treatment, may be performed after the process.

Meanwhile, the method of preparing a resin article may further includepreparing a second resin before the forming the resin blend. The secondresin may be selected depending on a first resin, as described above.For example, the second resin may be selected such that a value of asurface energy of the second resin is less than that of the first resin.Further, the second resin may be selected to add specific functions on asurface of the resin article. As examples for the preparation of thesecond resin, there is bulk polymerization, solution polymerization,suspension polymerization, or emulsion polymerization.

In the suspension polymerization method, the second resin may beprepared by dispersing a monomer in a reaction medium, adding andblending an additive such as a chain transfer agent, an initiator and adispersion stabilizer in the reaction solvent and polymerizing the blendat 40° C. or higher. One of skilled in the art can easily select thekind of monomer based on a desired function such as an abrasionresistance function, an anti-wear function, an anti-contaminationfunction, an anti-fingerprint function, a colored function, a pearlfunction, a high-gloss function, a non-gloss function and a batherfunction. By way of examples of the monomer, there are (meth)acrylatemonomers, epoxy monomers, oxetane monomers, isocyanate monomers, siliconmonomers, fluorine-based monomers or a copolymer thereof.

The reaction medium may be any medium known to be conventionally used toprepare a synthetic resin, polymer or copolymer without limitation. Forexample, the reaction medium may be distilled water. The chain transferagent which can be added to the reaction solvent may be, but is notlimited to, an alkyl or aryl mercaptan such as n-butyl mercaptan,n-dodecyl mercaptan, tertiary dodecyl mercaptan, isopropyl mercaptan oraryl mercaptan; a halogen compound such as ketone tetrachloride; or anaromatic compound such as an alpha-methylstyrene dimer or analpha-ethylstyrene dimer. The initiator is a polymerization initiator,which may be, but is not limited to, a peroxide such as octanoylperoxide, decanoyl peroxide or lauroyl peroxide, or an azo-basedcompound such as azobisisobutyronitrile orazobis-(2,4-dimethyl)-valeronitrile. The dispersion stabilizer which canbe included in the reaction medium may be, but is not limited to, anorganic distribution agent such as polyvinyl alcohol, polyolefin-maleicacid or cellulose, or an inorganic distribution agent such as tricalciumphosphate.

The first and second resins have already been described above in detail,and thus further description thereof will be omitted.

In addition, another embodiment of the present invention provides anautomobile part, a helmet, a part of electric device, a part of sewingmachine, toys or pipes that contain a melt-processed resin articledescribed above.

The present invention will be described with reference to the followingExamples in detail. However, the present invention is not limited to thefollowing Examples.

Measurement of Surface Energy

According to the Owens-Wendt-Rabel-Kaelble (OWRK) method, surfaceenergies of first resins and second resins were measured using a dropshape analyzer (Kruss, DSA100). More specifically, the first resins andsecond resins were dissolved in a methyl ethyl ketone solvent to have aconcentration of 15 wt %, and then coated on a LCD glass by bar coating.The coated LCD glass was pre-dried in an oven at 60° C. for 2 minutesand then dried at 90° C. for 1 minute. After drying (or curing),deionized water and diiodomethane were dropped 10 times on the coatedsurface at 25° C., respectively, to get an average value of a contactangle, and surface energy was calculated by substituting a numericalvalue into the OWRK method.

Measurement of Melt Viscosity

Melt viscosities of first resins and second resins were measured using aCapillary Rheometer 1501 (Gottfert). More specifically, after acapillary die was attached to a barrel, the first resins and secondresins were put into the barrel by dividing to 3 parts. A shearviscosity (pa*s) according to a shear rate of 100 to 1000 s⁻¹ wasmeasured at a processing temperature of 240° C.

Measurement of Solubility Parameter

While there are some methods of measuring and calculating solubilityparameters, the solubility parameters of first resins and second resinswere calculated at 25° C. using a known method, the Van Krevelen method[refer to Bicerano, J., Prediction of Polymer Properties, third edition,Marcel Dekker Inc., New York (2002), the disclosure of which isincorporated herein by reference in its entirety]. According to the VanKrevelen method, the solubility parameter was calculated using a groupcontribution theory, and defined as the following formula:

${\delta \mspace{14mu} \left( {{solubility}\mspace{14mu} {parameter}} \right)} = {\sqrt{e_{coh}} = \sqrt{\frac{E_{coh}}{V}}}$

In the formula, E_(coh) is a cohesive energy, V is a molar volume, ande_(coh) is a cohesive energy density. The cohesive energy (E_(coh)) isdefined as follows:

E _(coh)=10570.9×(⁰ X ^(v)−⁰ X)+9072.8×(2×¹ X− ¹ X ^(v))+1018.2×N _(VKH)

In the formula, ⁰X, ¹X, ⁰X^(v) and ¹X^(v) are connectivity indices, andN_(VKH) is a correlation term. Each variant was calculated withreference to the disclosed literature [Blicerano, J., Prediction ofPolymer Properties, third edition, Marcel Dekker Inc., New York (2002)].

Observation of Feature of Cross-Section

Samples went through a low temperature impact test. Then, fracturesurfaces of the samples were etched using THF vapor, and alayer-separated cross-section was observed using an SEM.

Meanwhile, to measure thicknesses of layer-separated first and secondresin layers and an interface layer, the samples of the followingExamples and Comparative Examples were cut with a diamond knife at −120°C. using a microtoming device (Leica EM FC6), thereby obtaining a smoothcross-section. The part of the sample with the microtomed smoothcross-section was dipped in a 1,2-dichloroethane solution (10 volume %,in EtOH) to etch for 10 seconds, and then washed with distilled water.The etched cross-sectional part was dissolved to different levels ofdepth according to the contents of the first and second resins, andcould be observed using an SEM. That is, when the cross-section wasviewed at a 45-degree angle from a surface, due to a shade difference,the first resin layer, the second resin layer and the interface layercould be observed, and a thickness of each layer could be measured.

Experiment for Measuring Pencil Hardness

Pencil hardness of samples was measured under a constant load of 500 gusing a pencil hardness tester (Chungbuk Tech). Scratches were made on asurface of the samples by standard pencils (Mitsubishi; grade 6B to 9H)with a fixed angle of 45 degrees, and therefore a change rate of thesurface was observed (ASTM 3363). The values of pencil hardness areaverage values of the results obtained from tests performed 5 times.

Measurement of Molecular Weight Distribution (PDI)

Molecular weight distribution was measured using gel permeationchromatography (GPC) under conditions as follows:

Instrument: 1200 series produced by Agilent Technologies

Column: 2 PLgel mixed Bs produced by Polymer Laboratories

Solvent: THF

Column Temperature: 40° C.

Concentration of Sample: 1 mg/mL, 100 L injection

Standard: Polystyrene (Mp: 3900000, 723000, 316500, 52200, 31400, 7200,3940 or 485)

As an analysis program, ChemStataion provided by Agilent Technologieswas used, and a weight average molecular weight (Mw) and a numberaverage molecular weight (Mn) were measured using gel permeationchromatography (GPC), and the molecular weight distribution was thencalculated from an equation of Mw/Mn.

Surface Analysis by IR Spectrometer

The experiment was performed using a UMA-600 IR microscope equipped witha Varian FTS-7000 spectrometer (Varian, USA) and a mercury cadmiumtelluride (MCT) detector, and detection of spectra and data processingwere performed using Win-IR PRO 3.4 software (Varian, USA). Conditionsof the experiment were as follows:

-   -   Germanium (Ge) ATR crystal having refractive index of 4.0    -   Spectral Resolution of Middle Infrared Spectrum obtained by        Attenuated Total Reflection: 8 cm⁻¹ and Range of 16 Scans: 4000        cm⁻¹-600 cm⁻¹.    -   Internal Reference Band: Carbonyl Group (C═O str., ˜1725 cm⁻¹)        of Acrylate    -   Original Component of First Resin: Butadiene Compound [C═C str.        (˜1630 cm⁻¹) or ═C—H out-of-plane vib. (˜970 cm⁻¹)]

Peak intensity ratios [I_(BD)(C═C)/I_(A)(C═O)] and[I_(BD)(out-of-plane)/I_(A)(C═O)] were calculated, and the detection ofspectra was performed 5 times in different regions of one sample, and anaverage value and a standard deviation were calculated.

EXAMPLE 1

(1) Preparation of First Resin and Second Resin

As a first resin, a first resin-1(a thermoplastic resin composed of 60wt % methyl methacrylate, 7 wt % acrylonitrile, 10 wt % butadiene and 23wt % styrene) was used. As a second resin, a second resin-1 was preparedas following: 1500 g of distilled water and 4 g of 2% polyvinylalcoholaqueous solution as a dispersing agent were put into a 3-liter reactorand dissolved. Subsequently, 560 g of methyl methacrylate, 240 g ofglycidyl methacrylate, 2.4 g of n-dodecyl mercaptan as a chain transferagent and 2.4 g of azobisisobutyronitrile as an initiator were furtheradded thereto, and mixed while stirring at 400 rpm. The mixture waspolymerized by 3-hour reaction at 60° C., and cooled to 30° C., therebyobtaining a bead-type second resin-1. Afterward, the second resin-1 waswashed three times with distilled water, dehydrated and dried in anoven.

As the results of measurement of the physical properties of the firstresin-1 and the second resin-1, it was shown that a difference insurface energy was 6.4 mN/m, a difference in melt viscosity was 180pa*s, a difference in solubility parameter was 0.5 (J/cm³)^(1/2), aweight average molecular weight of the second resin obtained by GPC was100K, and a molecular weight distribution (PDI) of the second resin was2.1.

(2) Preparation of Resin Blend and Resin Article Using the Same

After 90 parts by weight of the first resin-1 was blended with 10 partsby weight of the second resin-1, the blend was extruded using atwin-screw extruder (Leistritz) at 240° C., thereby obtaining a pellet.A layer separation was observed in the pellet. Then, the pellet wasinjected using an EC100Φ30 injector (ENGEL) at 240° C., therebyobtaining a sample 1 having a thickness of 3200 μm. A thickness of thesecond resin layer was 82 μm and a thickness of an interface layer was33 μm. A pencil hardness of the sample 1 was 2H, and layer separationoccurred. The feature of the cross-section of the sample 1 observed byusing SEM is shown in FIG. 3. Also, the feature of the cross-section ofthe sample 1 observed at a 45-degree angle from the surface is shown inFIG. 9. The peak intensity ratio [I_(BD)(C═C)/I_(A)(C═O)] measured by anIR spectrometer was averagely 0.0122 with a standard deviation of0.0004, and the peak intensity ratio [I_(BD)(out-of-plane)/I_(A)(C═O)]was averagely 0.411 with a standard deviation of 0.0026.

EXAMPLE 2

(1) Preparation of First Resin and Second Resin

As a first resin, the first resin-1 of Example 1 was used. As a secondresin, a second resin-2 was prepared as following: 1500 g of distilledwater and 4 g of 2% polyvinylalcohol aqueous solution as a dispersingagent were put into a 3-liter reactor and dissolved. Subsequently, 760 gof methyl methacrylate, 40 g of perfluorohexylethyl methacrylate, 2.4 gof n-dodecyl mercaptan as a chain transfer agent and 2.4 g ofazobisisobutyronitrile as an initiator were further added thereto, andmixed while stirring at 400 rpm. The mixture was polymerized by 3-hourreaction at 60° C., and cooled to 30° C., thereby obtaining a bead-typesecond resin-2. Afterward, the second resin-2 was washed three timeswith distilled water, dehydrated and dried in an oven.

As the results of measurement of the physical properties of the firstresin-1 and the second resin-2, it was shown that a difference insurface energy was 4.2 mN/m, a difference in melt viscosity was 250pa*s, a difference in solubility parameter was 0.2 (J/cm³)^(1/2), aweight average molecular weight of the second resin obtained by GPC was100K, and a molecular weight distribution (PDI) of the second resin was2.0.

(2) Preparation of Resin Blend and Resin Article Using the Same

A sample 2 having a thickness of 3200 μm was prepared by the same methodas Example 1, except that 10 parts by weight of the second resin-2 wasused instead of 10 parts by weight of the second resin-1. A thickness ofthe second resin layer was 102 μm and a thickness of an interface layerwas 15 μm. A pencil hardness of the sample 2 was 2H, and layerseparation occurred.

EXAMPLE 3

(1) Preparation of First Resin and Second Resin

As a first resin, the first resin-1 of Example 1 was used. As a secondresin, a second resin-3 was prepared by the same method as described inExample 1, except that 560 g of methyl methacrylate, 240 g of tertiarybutyl methacrylate, 2.4 g of n-dodecyl mercaptan as a chain transferagent and 3.2 g of azobisisobutyronitrile as an initiator were put intothe reactor.

As the results of measurement of the physical properties of the firstresin-1 and the second resin-3, it was shown that a difference insurface energy was 1.1 mN/m, a difference in melt viscosity was 360pa*s, a difference in solubility parameter was 0.7 (J/cm³)^(1/2), aweight average molecular weight of the second resin obtained by GPC was80K, and a molecular weight distribution (PDI) of the second resin was1.9.

(2) Preparation of Resin Blend and Resin Article Using the Same

A sample 3 having a thickness of 3200 μm was prepared by the same methodas Example 1, except that 10 parts by weight of the second resin-3 wasused instead of 10 parts by weight of the second resin-1. A thickness ofthe second resin layer was 79 μm and a thickness of an interface layerwas 24 μm. A pencil hardness of the sample 3 was 2H, and layerseparation occurred.

EXAMPLE 4

(1) Preparation of First Resin and Second Resin

As a first resin, a first resin-2(a thermoplastic resin composed of 21wt % of acrylonitrile, 15 wt % of butadiene and 64 wt % of styrene) wasused. As a second resin, the second resin-1 of Example 1 was used.

As the results of measurement of the physical properties of the firstresin-2 and the second resin-1, it was shown that a difference insurface energy was 6.1 mN/m, a difference in melt viscosity was 120pa*s, a difference in solubility parameter was 0.7 (J/cm³)^(1/2), aweight average molecular weight of the second resin obtained by GPC was100K, and a molecular weight distribution (PDI) of the second resin was2.1.

(2) Preparation of Resin Blend and Resin Article Using the Same

A sample 4 having a thickness of 3200 μm was prepared by the same methodas described in Example 1, except that 90 parts by weight of the firstresin-2 was used instead of 90 parts by weight of the first resin-1. Athickness of the second resin layer was 46 μm and a thickness of aninterface layer was 23 μm. A pencil hardness of the sample 4 was HB, andlayer separation occurred.

EXAMPLE 5

As a first resin, the first resin-1 of Example 1 was used. As a secondresin, a second resin-4 was prepared by the same method as described inExample 1, except that 592 g of methyl methacrylate, 160 g of phenylmethacrylate, 48 g of methacrylic acid, 2.4 g of n-dodecyl mercaptan asa chain transfer agent and 2.4 g of azobisisobutyronitrile as aninitiator were put into the reactor.

As the results of measurement of the physical properties of the firstresin-1 and the second resin-4, it was shown that a difference insurface energy was 2.0 mN/m, a difference in melt viscosity was 350pa*s, a difference in solubility parameter was 0.6 (J/cm³)^(1/2), aweight average molecular weight of the second resin obtained by GPC was100K, and a molecular weight distribution (PDI) of the second resin was2.2.

(2) Preparation of Resin Blend and Resin Article Using the Same

A sample 5 having a thickness of 3200 μm was prepared by the same methodas Example 1, except that 10 parts by weight of the second resin-4 wasused instead of 10 parts by weight of the second resin-1. A thickness ofthe second resin layer was 13 μm and a thickness of an interface layerwas 36 μm. A pencil hardness of the sample 5 was 1.5H, and layerseparation occurred.

COMPARATIVE EXAMPLE 1

Comparative Example 1 was prepared with only the first resin-1 ofExample. Particularly, 100 parts by weight of the first resin-1 ofExample 1 was extruded using a twin-screw extruder (Leistritz) at 240°C., thereby obtaining a pellet. Then, the pellet was injected using anEC100Φ30 injector (ENGEL) at 240° C., thereby obtaining a sample 6having a thickness of 3200 μm.

As the results obtained by measuring physical properties of the sample6, a pencil hardness was F, and layer separation was not observed.

COMPARATIVE EXAMPLE 2

100 parts by weight of the first resin-2 of Example 4 was extruded usinga twin-screw extruder (Leistritz) at 240° C., thereby obtaining apellet. Then, the pellet was injected using an EC100Φ30 injector (ENGEL)at 240° C., thereby obtaining a sample 7 having a thickness of 3200 μm.

As the results obtained by measuring physical properties of the sample7, a pencil hardness was 2B, and layer separation was not observed.

COMPARATIVE EXAMPLE 3

(1) Preparation of First Resin and Second Resin

As a first resin, the first resin-1 of Example 1 was used. As a secondresin, a second resin-5 was prepared as following: 1500 g of distilledwater and 4 g of 2% polyvinylalcohol aqueous solution as a dispersingagent were put into a 3-liter reactor and dissolved. Subsequently, 40 gof methyl methacrylate, 760 g of perfluorohexylethyl methacrylate, 2.4 gof n-dodecyl mercaptan as a chain transfer agent and 2.4 g ofazobisisobutyronitrile as an initiator were further added thereto, andmixed while stirring at 400 rpm. The mixture was polymerized by 3-hourreaction at 60° C., and cooled to 30° C., thereby obtaining a bead-typesecond resin-5. Afterward, the second resin-5 was washed three timeswith distilled water, dehydrated and dried in an oven.

As the results of measurement of the physical properties of the firstresin-1 and the second resin-5, it was shown that a difference insurface energy was 37 mN/m, a difference in melt viscosity was 375 pa*s,a difference in solubility parameter was 3.5 (J/cm³)^(1/2), a weightaverage molecular weight of the second resin measured by GPC was 100K,and a molecular weight distribution (PDI) of the second resin was 2.1.

(2) Preparation of Resin Blend and Resin Article Using the Same

A sample 8 having a thickness of 3200 μm was prepared by the same methodas described in Example 1, except that 10 parts by weight of a secondresin-5 was used instead of 10 parts by weight of the second resin-1. Adetachment between the first resin and the second resin in the sample 8occurred, and thus a pencil hardness was not measured.

COMPARATIVE EXAMPLE 4

(1) Preparation of First Resin and Second Resin

As a first resin, the first resin-1 of Example 1 was used. As a secondresin, a second resin-6 was prepared by the same method as described inExample 1, except that 0.8 g of n-dodecyl mercaptan and 1.6 g ofazobisisobutyronitrile were used instead of 2.4 g of n-dodecyl mercaptanand 2.4 g of azobisisobutyronitrile.

As the results of measurement of the physical properties of the firstresin-1 and the second resin-6, it was shown that a difference insurface energy was 6.3 mN/m, a difference in melt viscosity was 1090pa*s, a difference in solubility parameter was 0.5 (J/cm³)^(1/2), aweight average molecular weight of the second resin obtained by GPC was205K, and a molecular weight distribution (PDI) of the second resin was3.3.

(2) Preparation of Resin Blend and Resin Article Using the Same

A sample 9 having a thickness of 3200 μm was prepared by the same methodas Example 1, except that 10 parts by weight of the second resin-6 wasused instead of 10 parts by weight of the second resin-1. A pencilhardness of the sample 9 was H, layer separation was partially observed,and a thickness of separated layer was non-uniform in parts.

COMPARATIVE EXAMPLE 5

(1) Preparation of First Resin and Second Resin

As a first resin, the first resin-1 of Example 1 was used. As a secondresin, a second resin-7 was prepared by the same method as described inExample 3, except that 4.8 g of n-dodecyl mercaptan and 2.4 g ofazobisisobutyronitrile were used instead of 2.4 g of n-dodecyl mercaptanand 3.2 g of azobisisobutyronitrile.

As the results of measurement of the physical properties of the firstresin-1 and the second resin-7, it was shown that a difference insurface energy was 1 mN/m, a difference in melt viscosity was 610 pa*s,a difference in solubility parameter was 0.7 (J/cm³)^(1/2), a weightaverage molecular weight of the second resin was 42K, and a molecularweight distribution (PDI) of the second resin was 3.2.

(2) Preparation of Resin Blend and Resin Article Using the Same

A sample 10 having a thickness of 3200 μm was prepared by the samemethod as described in Example 3, except that 10 parts by weight of asecond resin-7 was used instead of 10 parts by weight of the secondresin-3. A pencil hardness of the sample 10 was F, and layer separationwas not observed.

COMPARATIVE EXAMPLE 6

(1) Preparation of First Resin and Second Resin

As a first resin, the first resin-1 of Example 1 was used. As a secondresin, a second resin-8 was prepared by the same method as described inExample 3, except that 0.5 g of n-dodecyl mercaptan and 1.6 g ofazobisisobutyronitrile were used instead of 2.4 g of n-dodecyl mercaptanand 3.2 g of azobisisobutyronitrile.

As the results of measurement of the physical properties of the firstresin-1 and the second resin-8, it was shown that a difference insurface energy was 1 mN/m, a difference in melt viscosity was 1390 pa*s,a difference in solubility parameter was 0.7 (J/cm³)^(1/2), a weightaverage molecular weight of the second resin was 245K, and a molecularweight distribution (PDI) of the second resin was 5.3.

(2) Preparation of Resin Blend and Resin Article Using the Same

A sample 11 having a thickness of 3200 μm was prepared by the samemethod as described in Example 3, except that 10 parts by weight of thesecond resin-8 was used instead of 10 parts by weight of the secondresin-3. A pencil hardness of the sample 11 was F, and layer separationwas not observed.

COMPARATIVE EXAMPLE 7

(1) Preparation of First Resin and Second Resin

As a first resin, the first resin-1 of Example 1 was used. As a secondresin, a second resin-9 was prepared by the same method as described inExample 3, except that 0.4 g of n-dodecyl mercaptan and 1.1 g ofazobisisobutyronitrile were used instead of 2.4 g of n-dodecyl mercaptanand 3.2 g of azobisisobutyronitrile.

As the results of measurement of the physical properties of the firstresin-1 and the second resin-9, it was shown that a difference insurface energy was 1 mN/m, a difference in melt viscosity was 2200 pa*s,a difference in solubility parameter was 0.7 (J/cm³)^(1/2), a weightaverage molecular weight of the second resin was 320K, and a molecularweight distribution (PDI) of the second resin was 5.2.

(2) Preparation of Resin Blend and Resin Article Using the Same

A sample 12 having a thickness of 3200 μm was prepared by the samemethod as described in Example 3, except that 10 parts by weight of thesecond resin-9 was used instead of 10 parts by weight of the secondresin-3. A pencil hardness of the sample 12 was F, and layer separationwas not observed.

COMPARATIVE EXAMPLE 8

A hard coating layer was formed on the sample 6 of Comparative Example 1by forming a layer by coating a hard coating solution prepared by theinventor including a multifunctional acrylate (19 wt % DPHA, 10 wt %PETA, 5 wt % urethane acrylate EB 1290 from SK cytech, 45 wt % methylethyl ketone, 20 wt % isopropyl alcohol and 1 wt % IRGACURE 184 as a UVinitiator from Ciba) using a Mayer bar #9 and drying the coating at 60to 90° C. for 4 minutes to form a coating film, and curing the coatingfilm by UV irradiation with an intensity of 3000 mJ/cm².

A pencil hardness of the hard coating layer was 3H, and average valuesand standard variations of peak intensity ratios[I_(BD)(C═C)/I_(A)(C═O)] and [I_(BD)(out-of-plane)/I_(A)(C═O)] detectedby an IR spectrometer were 0, respectively.

As shown in Examples 1-5 and Comparative Examples 1-8, the layerseparation was observed in Examples 1 to 5 using the first resin andsecond resin having the difference in surface energy, melt viscosity orsolubility parameter as described herein. It was further observed thatthe resin article prepared according to Examples 1 to 5 had a layerformed of the first resin, a layer formed of the second resin and aninterface layer including the first resin and the second resin. Here,the first resin layer constituted the body of the resin article and thesecond resin layer constituted the surface on the body.

As the second resin layer was formed on a surface of the resin articleby the melt processing, the resin article can have improved surfacecharacteristics. More particularly, since the second resin polymerizedfrom a methyl methacrylate-based monomer, as illustrated in Examples 1to 5, could exhibit an excellent anti-scratch characteristic due to ahigh pencil hardness of HB or more, the resin article showed an improvedhardness property. Although the hardness property was illustrated in theExamples 1-5 for the purpose of the description of the presentinvention, it will be obvious to one of skilled in the art that anyother property can be added to the second resin to improve a property ofa resin article.

On the other hand, the resin articles prepared using only the firstresin (Comparative Examples 1 and 2) did not have separated layers andhad low surface pencil hardness. Accordingly, to use the resin articleobtained in Comparative Examples 1 and 2 for a part of an automobile ora part of an electric device, a coating process was needed to improve asurface characteristic.

Meanwhile, when the difference in surface energy between the first resinand the second resin was greater than 35 mN/m (Comparative Example 3),the first resin was not attached to the second resin and both resinswere detached from each other. Therefore, it was understood that layerseparation occurred in the resin article only when the first resin andthe second resin had a certain difference in surface energy (at 25° C.)like Examples 1 to 5.

In addition, it was understood from Comparative Examples 4 to 7 that thelayer separation was observed only when the second resin had weightaverage molecular weight and molecular weight distribution as describedthe above.

As shown in Example 1 and Comparative Example 8, it was confirmed thataccording to the analysis of the surface of the second resin layer by anIR spectrometer, components of the first resin layer were detected inExample 1, but were not detected in Comparative Example 8 in which thelayer was hard-coated by a separate process.

While the invention has been shown and described with reference tocertain exemplary embodiments thereof, it will be understood by thoseskilled in the art that various changes in form and details may be madetherein without departing from the scope of the invention as defined bythe appended claims.

What is claimed is:
 1. A resin article, comprising: a first resin layer;and a second resin layer formed on the first resin layer, wherein thecomponent of the first resin layer is detected on a surface of thesecond resin layer by infrared spectrometer.
 2. The resin articleaccording to claim 1, further comprises an interface layer including afirst resin and a second resin and formed between the first resin layerand the second resin layer.
 3. The resin article according to claim 2,wherein the interface layer has a thickness of 0.01 to 95% based on thetotal thickness of the second resin layer and the interface layer. 4.The resin article according to claim 1, wherein the second resin layerhas a thickness of 0.01 to 60% based on the total thickness of the resinarticle.
 5. The resin article according to claim 1, wherein the firstresin layer and the second resin layer has a difference in surfaceenergy at 25° C. of 0.1 to 35 mN/m.
 6. The resin article according toclaim 1, wherein the first resin layer and the second resin layer have adifference in melt viscosity of 0.1 to 3000 pa*s at a shear rate of 100to 1000 s⁻¹ and a processing temperature of the blend of the first resinand the second resin.
 7. The resin article according to claim 1, whereinthe first resin layer and the second resin layer have a difference insolubility parameter at 25° C. of 0.001 to 10.0 (J/cm³)^(1/2).
 8. Theresin article according to claim 1, wherein the second resin layer has amolecular weight distribution of 1 to 2.5
 9. The resin article accordingto claim 1, wherein the second resin layer has a weight averagemolecular weight of 30,000 to 200,000.
 10. The resin article accordingto claim 1, wherein the first resin layer includes at least one selectedfrom the group consisting of a styrene-based resin, a polyolefin-basedresin, a thermoplastic elastomer, a polyoxyalkylene-based resin, apolyester-based resin, a polyvinyl chloride-based resin, apolycarbonate-based resin, a polyphenylene sulfide-based resin, a vinylalcohol-based resin, an acrylate-based resin, engineering plastics and acopolymer thereof.
 11. The resin article according to claim 1, whereinthe second resin layer includes at least one selected from the groupconsisting of a high surface hardness resin, an anti-wear resin, ananti-contamination resin, an anti-fingerprint resin, a colored resin, apearl resin, a high-gloss resin, a non-gloss resin and a barrier resin.12. The resin article according to claim 1, wherein the second resinlayer includes at least one selected from the group consisting of a(meth)acrylate-based resin, an epoxy-based resin, an oxetane-basedresin, an isocyanate-based resin, a silicon-based resin, afluorine-based resin and a copolymer thereof.